Effect of Application of Biochar and Wood Vinegar on Some Chemical and Microbiological Properties of Soil under Forage Corn Cultivation

Different agricultural policies tend to minimize the environmental risks caused by the continuous use of pesticides and other synthetic chemicals and look for alternative methods. Wood vinegar and biochar can be used in organic agriculture as soil conditioners. This study aimed to investigate the effect of biochar and wood vinegar on some chemical and microbiological properties of soil under forage corn cultivation.

For this purpose, a research was carried out in greenhouse condition. The experiment was a factorial experiment in a completely randomized design in 3 replications. The studied treatments include wood vinegar in 6 amounts of zero (W0), 0.02 (W1), 0.04 (W2), 0.1 (W3), 0.2 (W4), and 0.4 (W5) g/Kg (first factor) and soil conditioner including raw material (wood of pomegranate and plum trees) in 2 levels 1% (B01) and 2% (B02) amounts and biochar (biochar prepared from pomegranate and plum trees at temperature 4500C) was applied at 2 levels of 1% (B1) and 2% (B2) amounts (second factor). The chemical properties of the soils such as soil acidity (pH), electrical conductivity (EC), soil organic carbon (OC), total nitrogen (TN), soluble sodium (Na+), soluble potassium (K+), soluble calcium (Ca+2), soluble magnesium (Mg+2) and available phosphorous (P); and the soil microbiological properties including basal respiration and microbial biomass carbon and the physical characteristics of forage corn such as height, stem diameter, dry weight, and wet weight were measured.

The results showed that co-application of conditioner and wood vinegar increased soil acidity (5.3%), electrical conductivity (EC), soluble calcium (Ca+2), soluble magnesium (Mg+2), organic carbon (OC), basal respiration, and microbial biomass carbon. The most significant increase in electrical conductivity (EC), soluble calcium (Ca+2), soluble magnesium (Mg+2), and organic carbon (OC) were observed in W5B2 treatment, which were 5.3, 3.9, 2.2, 3.6, and 7.2 times more than the control. Also, the basal respiration with the highest amount of emitted CO2 during one month of incubation in all three times intervals was observed in W5B2 treatment. So that in the first, second, and third ten days, the rate of soil microbial respiration in W5B2 treatment was observed 6.91, 6.54, and 6.4 times more than the control, respectively. The co-application of wood vinegar and biochar led to increase in the stem diameter, dry weight, and wet weight of the plant. In contrast, the co-application of wood vinegar and the soil conditioner decreased the plant's stem diameter, wet and dry weight compared to the control. Addition of conditioner material alone increased soluble sodium (Na+), soluble potassium (K+), Fe, Cu, Zn, and Mn, while decreasing total nitrogen (TN) and available phosphorous (P).

The results illustrated that the effect of using biochar and wood vinegar on increasing, the concentration of elements and improving the qualitative characteristics of soil and plants depends on the amount of nutrients, organic carbon in biochar and wood vinegar, soil acidity and their consumption. Considering the positive effect of biochar and wood vinegar on increasing soil organic carbon, increasing the availability of nutrients, stimulating soil microbial activity and increasing plant growth, it is recommended to use biochar and wood vinegar in calcareous soils of Iran.